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Corn Harvest, Drying Challenging Again This Year

Producers need to check the condition of their corn crop in the field.

Drought conditions stressed this year’s corn crop, leading to weak stalks and shanks.

Weak stalks contribute to “downed” corn due to wind or other forces, and weak shanks contribute to ear drop and large field losses.

“Farmers need to check the condition of the corn in the field,” says North Dakota State University Extension Service agricultural engineer Ken Hellevang.

Drought conditions also are leading to larger than normal in-field corn moisture content variations. Reports indicate the moisture content varies from 15 to 25 percent in the same field due to soil variations or other contributing factors. If kernel size or density varies along with the moisture content, the result could be pockets of wet corn in a bin. That occurs when grain segregates based on size and density as it flows into a bin.

“Generally, the smaller and denser material will accumulate in the center and the larger material flows to the perimeter of the bin,” Hellevang says. “Using a distributor or ‘coring’ the bin may reduce the accumulation of smaller material in the center of the bin.”

A September harvest also may cause in-bin drying problems. A natural-air drying system that provides an airflow rate of 1 cfm/bu (cubic feet per minute of airflow per bushel of corn) will dry 20 percent moisture corn to about 14 percent with average October ambient air conditions of 50 degrees and 65 percent relative humidity. The estimated drying time is about 37 days, and the allowable storage time (AST) of 20 percent moisture corn at 50 degrees is about 65 days.

Average ambient air conditions for September are 60 degrees and 65 percent relative humidity. An air drying system in September will dry 20 percent moisture corn to about 13 percent in about 37 days. The drying time is the same because the corn is dried to 13 percent in September and 14 percent in October, so more moisture is being removed during September.

The concern with drying in September is that the AST is reduced to about 28 days. The drying time exceeds the AST, so a quality loss may occur before the corn gets dry and the entire storage life of the corn has been used. Thus, problems also may develop during storage.

The drying speed is related to the airflow rate, so the drying speed can be increased by not filling the bin with corn. For example, if the bin is only one-half full, the expected airflow rate will be about 2 cfm/bu and the drying rate twice what it is with an airflow rate of 1 cfm/bu.

Running the fan only at night to dry with cooler air will lengthen the AST, but it also will lengthen the drying time. For example, running the fan for 12 hours at night during September will reduce the average air temperature to about 50 degrees, so the AST is extended to about 50 days. However, the drying time also will be extended to about 75 days due to the fan only operating for one-half of the day.

“The storage life of corn produced this year may be shorter than normal, so farmers need to be more diligent with drying and storage management,” Hellevang says. “This is because the storage life of grain grown under stressful conditions is normally shorter than that of grain developed without plant stress.”